Pressure groups are doing their best to suppress corporate political opinions.

The battle for free speech did not start or end with Citizens United. Four years ago, that Supreme Court decision reaffirmed the right of corporations, including nonprofits, to independently spend money urging voters to elect or defeat candidates. Ever since, those opposed to the First Amendment have explored every conceivable avenue to limit corporations from doing so.

The efforts began almost immediately after the decision. President Obama publicly lambasted Citizens United in his 2010 State of the Union address, suggesting that nefarious characters would exploit it at the expense of our democracy. Senator Chuck Schumer (D., N.Y.) announced his intent to introduce legislation that would force corporations to publicly disclose their political expenditures, noting that the “deterrent effect [of disclosure] should not be underestimated” and that it would make corporations “think twice” about engaging in politics.

Within four months of the decision, the Internal Revenue Service began flagging conservative groups for additional scrutiny. Unable to target money at its source, members of Congress and activist groups actively pressured the IRS to investigate right-leaning organizations, hoping that by harassing the recipients of corporate support, they can mute the effects of Citizens United.

Eight months after the ruling, President Obama began publicly suggesting that organizations that accepted corporate support were engaged in foul play, and calling politically engaged nonprofits “destructive to our democracy.”

By 2011, the war on corporate speech had taken a decidedly personal turn, with the IRS singling out donors to the conservative nonprofit Freedom’s Watch for audit. The IRS also decided to impose gift taxes on the donors’ contributions, something the agency hadn’t done with such groups in over 20 years. The agency backed off of this course only after an outcry from a bipartisan group of nonprofit tax lawyers.

With the assault against recipients of donations in full swing, other groups of anti-speech activists decided to attack political money on another front.

Though they are unable to impose legislative limits on corporate nonprofit donors, coalitions of investors, academics, and activists use a stick-and-carrot approach to discourage public corporations from engaging in politics. It goes like this: Groups go to corporations with the message that engaging in political activity can be harmful to shareholder value, and therefore the corporation should disclose its political activities to the public. The more the corporation complies with the request, the higher it ranks in studies of political accountability and the more it is publicly lauded by activists. If the corporation does not comply, it ranks lower in the studies and is subjected to a negative media campaign by the activists.

But even if a corporation complies with the initial demands, the campaign doesn’t end there. The studies change their criteria year to year in order to gradually draw greater concessions from previously targeted companies.

This is hardly a comprehensive list of avenues explored by the pro-regulation community in its quest to clamp down on political spending since Citizens United. Activists have mounted a letter-writing campaign asking the Securities and Exchange Commission to enact intrusive, unnecessary disclosure requirements on public corporations. Others have focused on pressuring the Federal Communications Commission to adopt unprecedented and extensive disclosure regulations, such as requiring television stations to name donors who provide 10 percent or more of an advertisement’s funding. Thus far the agency has rejected these rules.

Americans trying to speak about candidates and issues, as is their First Amendment right, have faced a government uninterested in ensuring that our political debate is robust, diverse, and wide-open, and activists intent on pressuring them into silence. But despite all these efforts and political abuse by the IRS, free-speech advocates have so far emerged mostly victorious, and all of us who prize vigorous participation in the public square should be thankful.

— Joe Trotter is the media manager for the Center for Competitive Politics.